| Autor: |
Schoenenberger, Cora-Ann, Zuk, Anna, Zinkl, Gregory M., Kendall, Donna, Matlin, Karl S. |
| Zdroj: |
Journal of Cell Science; February 1994, Vol. 107 Issue: 2 p527-541, 15p |
| Abstrakt: |
Epithelial cells polarize in response to contacts with the extracellular matrix and with neighboring cells. Interac-tions of cells with the extracellular matrix are mediated mainly by the integrin family of receptors. To begin to understand the role of integrins in polarization, we have investigated the expression and localization of three integrin families in the polarized Madin-Darby canine kidney (MDCK) epithelial cell line and in transformed MDCK cells lacking apical polarity. We find that MDCK cells express several β1 integrins, including α2β1, α3β1, and an unidentified integrin designated αxβ1. The β1 integrins are the major receptors for collagens I and IV and laminin in MDCK cells, since a blocking anti-β1 antibody almost totally abolishes adhesion to these proteins. They also express a vitronectin receptor tentatively identified as αvβ3, and the epithelial-specific integrin α6β4. The latter is not a laminin receptor in MDCK cells because a function blocking anti-α6 antibody has no effect on cell adhesion to laminin. All three integrin families are expressed exclu-sively on both the basal and lateral surfaces, as determined by immunofluorescence microscopy and surface biotinyla-tion. Transformed MDCK cells express β1 integrins as well as αvβ3 and α6β4, but show alterations in the β1 family. Expression of αx is lacking, and the relative amount of the β1 subunit is diminished, resulting in the accumulation of Endo-H-sensitive α3. In addition, surface biotinylation and immunofluorescence indicate that significant amounts of both α2β1 and α3β1 appear on not only the basolateral but also the apical plasma membrane. These results indicate that integrins are the major receptors for the extracellular matrix in MDCK cells, and that they may affect epithelial cell polarization by mediating not only cell-substratum but also cell-cell contacts. |
| Databáze: |
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